Thermoplastic fiber with excellent durability and fabric comprising the same

ABSTRACT

Disclosed are a thermoplastic fiber with excellent durability and a fabric comprising the same. More particularly, the thermoplastic fiber contains fluoropolymer particles with average particle diameter ranging from 0.01 to 5.0/ΛII in thermoplastic resin to form the fiber. The inventive thermoplastic fiber is prepared by adding the fluoropolymer particles to the thermoplastic resin while spinning the thermoplastic resin. The inventive thermoplastic fiber exhibits superior durability, that is, resistance to friction and/or modification and is preferably adopted as yarns for footwear, furniture, (mountain-climbing) backpacks, abrasives, sportswear and so on.

TECHNICAL FIELD

The present invention relates to a thermoplastic fiber with excellent durability and a fabric comprising the same, and more particularly, to a thermoplastic fiber with excellent durability in response to friction and/or modification, which includes fluoropolymer particles with average particle diameter ranging from 0.01 to 5.0 μm in thermoplastic resin to form the fiber, as well as a fabric comprising the thermoplastic fiber.

BACKGROUND ART

In order to improve durability of a thermoplastic fiber made of polyamide and/or polyethylene terephthalate, the following methods well known in prior art are principally used.

The first method is to enhance mechanical properties of a yarn itself by increasing molecular weight of a base resin for the thermoplastic fiber during the polymerization process.

The second method is to increase a basic thickness of a thermoplastic fiber bundle during the spinning process of yarns. That is, as overall fiber fineness is increased, a load level applied to unit area is decreased. It is generally known that a fiber with 10 denier is stronger than that with 1 denier and a fiber with 1.00 denier is stronger than that with 10 denier.

The third method is to increase strength of a yarn through multiple-staged drawing and heat treatment by treating the yarn to have high orientation and/or crystallization while spin-drawing the yarn under a specific condition satisfying at least one or two of the above two conditions by altering conditions for drawing yarns.

The increase of molecular weight of the basic resin to form the thermoplastic fiber during the polymerization process, is accomplished by methods generally classified into two kinds of method. One of the methods is an extension of polymerization time period because molecular weight of a polymer is increased as the time is extended. However, this originally has limits in view of processing time and efficiency. For polyethylene terephthalate, a rate of increasing initial molecular weight has a linear correlation to time, but the increase of molecular weight depending on time tends to be considerably slowed with intrinsic viscosity in a range of more than 0.6. That is, there is a problem in that the molecular weight is rarely increased due to time required for the polymerization. Moreover, the molecular weight tends to be reduced due to side reactions, after reaching a peak of the intrinsic viscosity at a constant level.

In order to overcome the above problems, polyethylene terephthalate is polymerized with the intrinsic viscosity ranging from 0.5 to 0.7, passed through a solid state polymerization dryer which can uniformly apply high temperature of more than 150° C. to the polymer, thereby improving crystallization of the polymer. This commonly called “solid state polymerization” and usually increases intrinsic viscosity of polymer to a level ranging from 1.0 to 1.3. Such method causes significant time loss and productivity, and also incurs a heavy loss in view of production cost. Especially, in a case that time and hot air blowing are undesirably controlled during the solid state polymerization, there will be additional problems, for example, such that polyester portions may be agglomerated and adhered together while polyamide materials may cause change of colors such as yellowing. Accordingly, the solid state polymerization has difficulties in being adopted for general applications except special uses.

The other method is to ensure desirable durability and friction resistance ability of a yarn while increasing overall fineness thereof during the spinning process, which exhibits a disadvantage of limited increasing of fineness dependent on uses of the method. For example, a garment fabric formed using the yarn preferably has a standard weight ranging from 50 to 300 g/m². If the standard weight is below the lower limit, the yarn is too soft to perform weaving and/or knitting thereof. In contrast, for the standard weight of above the upper limit, a garment formed using the garment fabric is so heavy that a consumer hardly wears the garment, and is restricted in common daily life activity. In particular, when the fineness is increased, there is a reduction of soft feeling and flexibility of the fabric itself leading to stiffness of the fabric. Consequently, the fiber has limited fineness depending on uses thereof.

Furthermore, it is known that a method for increasing strength of a yarn by alteration of drawing conditions includes multi-staged drawing processes, for example, two-staged, three-staged or four staged process dependant upon purposes of use thereof, widely employed rather than a single drawing process. The multi-staged drawing process allows increase of strength in return for elongation reducing rate of the yarn according to multiple steps of the drawing process. Further heat treatment is effectively practiced together with the drawing process.

However, the multi-staged heat treatment process has expected limitations. More particularly, after producing a preformed yarn, the produced yarn is sometimes kept without any additional process for a constant period of time, then, is subjected to re-drawing by a multi-staged drawing device. Otherwise, the yarn is produced by a multi-stepped spinning immediate drawing device. However, the above heat treatment needs a great dimension of apparatus, exhibits reduced final drawing and winding rate in contrast to initial spinning speed and lower productivity, and has difficulties in processing to possibly cause lowered yield. Therefore, this process is not recommended in view of productivity.

The above conditions for improvement of durability are basic conditions for reducing weight of fibers or fabrics. But, many cases require premise conditions commercially available for reduction of the weight. If appropriate durability is ensured, weight reduction effect can be embodied by a thin fabric with lower fineness and, additionally, weight of the fabric is reduced while maintaining the same apparent form of the fabric.

Most of the cases are involved in the latter, such that the apparent form should be continuously unchanged, although the weight is reduced. These cases cannot often accept decrease of fabric density and thickness caused by using microfine yarns.

Under these circumstances, the most preferable fabrics comprise hollow fibers, and apparent specific gravity of a yarn is lowered to less than 1.0, that is, the constant specific gravity of water. Particularly, a polyamide fabric must accomplish a weight reduction rate of more than about 15% by weight while polyester fabric needs a weight reduction rate of more than about 25% by weight, in order to reduce the apparent specific gravity below 1.0 and, in turn, achieve the weight reduction. Herein, the internal hollow rate is determined by measuring a ratio of total area of hollow portions in cross-sectional area of the fiber relative to overall cross-sectional area of the fiber.

For the hollow fiber, the internal hollow rate is one of conditions for the weight reduction. Although apparent weight reduction is accomplished by increasing the internal hollow rate, strength and elongation of the yarn itself are substantially decreased. The hollow fiber generates markedly higher spinning draft by 5 to 10 times than that of typical yarns having circular cross-sectional areas according to conventional processes, leading to reduction of both of strength and elongation of the yarn itself. Accordingly, even though the yarn satisfies the conditions for polymerization, spinning and drawing processes, durability of the hollow fiber is rapidly decreased. When comparing durability of the above hollow fiber with that of a fiber having the same fineness or reduced weight, the durability of the hollow fiber is also considerably lowered. This is because a severe modification was caused by effective reduction of cross-sectional area and a substantially excessive drawing process.

Meanwhile, sea-island type composite fibers (often referred to as “sea-island fiber”) are complicated yarns commonly prepared using thermoplastic resin as island components and alkali release-elution type resin as sea components, which are mostly used in manufacturing ultra-fine yarns that comprise only island components of the sea-island fibers on a fabric by eluting the island components during processing after production of the fabric, and preparing microfine yarns from the sea-island fibers.

Such sea-island fibers generally used to prepare artificial leather or suede fabrics, become ultra-fine yarns with monofilament fineness ranging from 0.0001 to 0.3 denier. Polyester yarns comprising the ultra-fine yarns have diameter ranging from 0.1 μm to 3 μm. Due to ultra fineness, a fabric manufactured has inherent properties such as very soft touch feel and lightening effect (that is, weight reduction effect), so as to establish a territory of important synthetic fabric fields.

However, frictional durability of an ultra-fine yarn is significantly poor due to ultra fineness even though strength and durability per unit fineness are excellent, as converted into 1 denier of ultra-fine yarn bundle. Conventional artificial leathers or suede fabrics manufactured using the ultra-fine yarn have been restricted to uses for garments, however, use of these fabrics continues to expand into non-textile products such as furniture and bedding, and/or industrial applications such as for abrasives, wiping cloths, etc.

These trends require improvement of mechanical properties together with inherent properties of suede fabric. In other words, in order to expand use of the fabric into non-textile products or industrial applications, durability of the fabric often called frictional fastness/abrasion resistance must be enhanced. At present, the frictional fastness is not favorable and stands on a level in the range from grade 1 to grade 2.

DISCLOSURE OF THE INVENTION Technical Problem

Accordingly, the present invention is directed to solve the problems described above in regard to difficulties in improving durability of yarns and an object of the present invention is to provide a novel thermoplastic fiber with excellent durability and fabrics comprising the same.

Another object of the present invention is to provide a thermoplastic hollow fiber with light weight as well as excellent durability and a fabric comprising the same.

Another object of the present invention is to improve durability, especially, frictional fastness and abrasion resistance of an ultra-fine yarn comprising only island components of a sea-island type composite fiber by eluting sea components of the sea-island fiber.

A still further object of the present invention is to improve durability of a sea-island fiber sufficient to be used as a yarn for furniture, bedding, abrasive materials, etc. as well as a yarn for garments.

Technical Means to Solve the Problem

Hereinafter, the present invention is described in detail.

A thermoplastic fiber of the present invention which comprises thermoplastic resin, contains fluoropolymer particles with average particle diameter ranging from 0.01 to 5.0 μm in the thermoplastic resin.

The fluoropolymer includes at least one selected from a group consisting of polytetrafluoroethylene polymer, copolymer of tetrafluoroethylene and hexafluoropropene, copolymer of tetrafluoroethylene and perfluoroalkylvinylether, and terpolymer thereof.

Examples of perfluoroalkylvinylether perfluoropropylvinylether, perfluoroethylvinylether and the like.

The fluoropolymer particles are contained in the thermoplastic resin to form the thermoplastic fiber, so as to reduce friction coefficient of the fiber.

Briefly, the fluoropolymer particles in the thermoplastic resin reduce metal friction coefficient of a yarn and, in turn, protect the thermoplastic fiber itself when the particles are placed on surface of the fiber.

Content of the fluoropolymer particles preferably ranges from 0.1 to 9.0% by weight.

With the content of less than 0.1% by weight, it is difficult to ensure desired abrasion resistance and durability of the fiber. On the other hand, if the content exceeds 9.0% by weight, the fiber exhibits preferable abrasion resistance and durability over the desired level. However, the fiber also has excess tensile strength and frictional properties over desired levels suitable to manufacture yarns, thus, may cause significant trouble and/or very poor processing during spinning including, for example: extreme vibrations of a yarn guide; collapse of a yarn guide independent of yarn winding angles on a winding drum, etc.

The fluoropolymer particles have average particle diameter ranging from 0.01 to 5.0 μm, more preferably, from 0.1 to as determined by a microscope or an electron microscope. With less than 0.01 μm, there are difficulties in overcoming agglomeration of particles due to breaking fluoropolymer into particles and microfine diameter thereof. In contrast, when the particle diameter exceeds 5.0 μm, the particles as a mineral material show no continuity and serve as the weakest point during the spinning in production of fibers using the thermoplastic resin, therefore, may become a direct cause of yarn cutting or reduction of processing ability.

The thermoplastic fiber according to the present invention may comprise common yarns composed of thermoplastic resin, sea-island type composite fibers in which island components with monofilament fineness ranging from 0.01 to 0.3 denier are dispersed in sea components composed of alkali releasing and eluting polymer, thermoplastic hollow fiber having hollow portions in cross-sectional area of the fiber, and so on.

When the thermoplastic fiber is the sea-island fiber, fluoropolymer particles having average particle diameter ranging from 0.01 to 5.0 μm are contained in island components of the fiber.

A hollow rate of the thermoplastic hollow fiber preferably ranges from 10 to 40% dependent on types of the thermoplastic resin. With a hollow rate of less than 10%, there is substantially little effect of weight reduction. If the hollow rate is more than 40%, even well formed hollows may be easily collapsed by external force.

The present invention further provides a fabric comprising the thermoplastic fiber which contains fluoro polymer particles with average particle diameter ranging from 0.01 to 5.0 μm in thermoplastic resin. Content of the thermoplastic fiber preferably ranges from 40 to 100% by weight.

ADVANTAGEOUS EFFECTS

The fabrics manufactured by the present invention exhibit excellent durability and lightness, that is, weight reduction effect.

For example, in case of a polyester carpet requiring a constant abrasion resistance number of 2,000 times under ASTM-D3884 conditions, carpets manufactured using conventional polyester yarns with 150 denier rarely have an abrasion resistance of more than 1,400 times although texture of the carpet and conditions for a dyeing process are advantageously altered.

However, the thermoplastic fiber (common fiber) according to the present invention can produce a carpet with a specific abrasion resistance number of more than 2,000 times even by using the fiber with 150 denier.

In addition, a material in 75 denier grade originally having an abrasion resistance number of about 350 times can increase the abrasion resistance number to more than 500 times, and further enhance abrasion resistance after a false twisting process.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects, features and advantages of the present invention will become more apparent to those skilled in the related art in conjunction with the accompanying drawings. In the drawings:

FIG. 1 and FIG. 2 are illustrative cross sectional views of thermoplastic hollow fibers according to the present invention, respectively.

DESCRIPTION OF SYMBOLS FOR MAJOR PARTS IN DRAWINGS

-   -   1: hollow fiber     -   A: thermoplastic resin     -   B: hollow portion

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail from the following examples and comparative examples with reference to the accompanying drawings. However, these are intended to illustrate the invention as preferred embodiments of the present invention and do not limit the scope of the present invention.

Example 1

Using polyethylene terephthalate as a base polymer, a master batch containing 15% by weight of polytetrafluoroethylene particles, which have average particle diameter of 0.5 μm as measured by an electron microscope, was prepared.

With the prepared master batch and the base polymer of polyethylene terephthalate, a polyethylene terephthalate fiber comprising 36 filaments with 75 denier was produced by a spinning and direct drawing process. Content of polytetrafluoroethylene particles in the fiber was controlled to 1% by weight by regulating content of the master batch.

88 strands of the fibers were produced in a drum with 4 kg capacity, woven by means of an interlock circular knitting machine with 22 gauge, and dried at a rate of 30 m/min using a hot air dryer after dyeing at 130° C. for 60 minutes to produce a circular knitted fabric.

A result of measuring an abrasion resistance number of the produced fabric is shown in Table 1.

Example 2

A polyethylene terephthalate fiber and a circular knitted fabric comprising the same were prepared by the same procedure as in Example 1, except that average particle diameter of the above polytetrafluoroethylene particles was altered to 1.0 μm and content of the particles in the polyethylene terephthalate fiber was altered to 2%.

A result of measuring an abrasion resistance number of the produced fabric is shown in Table 1.

Example 3

A circular knitted fabric was produced under the same conditions described in Example 1 by using a false twisted yarn based on polyethylene terephthalate, which was prepared by false twisting a polyethylene terephthalate fiber (containing 1% by weight of polytetrafluoroethylene in the fiber) obtained under the same conditions described in Example 1.

A result of measuring an abrasion resistance number of the produced fabric is shown in Table 1.

Example 4

A circular knitted fabric was produced under the same conditions described in Example 2 by using a false twisted yarn based on polyethylene terephthalate, which was prepared by false twisting polyethylene terephthalate fibers (containing 2% by weight of polytetrafluoroethylene in the fiber) obtained under the same conditions described in Example 2.

A result of measuring an abrasion resistance number of the produced fabric is shown in Table 1.

Example 5

Using polyethylene terephthalate as a base polymer for island components of a fiber, a master batch containing 15% by weight of polytetrafluoroethylene particles, which have average particle diameter of 2.0 μm as measured by an electron microscope, was prepared.

With the prepared master batch, a 36 split type sea-island composite fiber comprising 24 filaments with 75 denier was produced by a spinning and direct drawing process. Content of the island components in the fiber were about 70% by weight while sea components of the fiber based on alkali releasing and eluting polymer were added in an amount of about 30% by weight. Content of polytetrafluoroethylene particles in the island components was controlled to 1% by weight by regulating content of the master batch.

88 strands of the sea-island fibers were prepared in a drum with 4 kg capacity, false twisted and combined with a highly shrinkable yarn comprising 12 filaments with 30 denier, which represents shrinkage of 25% when immersed into hot water at 100° C. for 30 minutes, so as to produce a yarn comprising 36 filaments with 105 denier. After weaving the yarn by means of an interlock circular knitting machine with 32 gauge, the woven fabric underwent a shrinkage process using a raising machine and a shearing process to obtain a base fabric. Subsequently, a strong alkaline NaOH solution with 50% purity was added to the base fabric in hot water at 100° C. to control overall concentration of a weight reducing solution to 1% by weight. Herein, a ratio by weight of total amount of the solution to weight of the fabric is controlled to 40:1. Using the solution, the weight of the fabric was reduced by about 24% by weight relative to total weight of the fabric over a period of 60 minutes, followed by scouring and washing processes. The treated fabric was subjected to a dyeing process at 130° C. for 60 minutes and a drying process using a hot air dryer at 180° C. and a rate of 30 m/min. After brushing, a circular knitted fabric was obtained as the final product.

A result of measuring an abrasion resistance number of the produced fabric is shown in Table 1.

Example 6

Using polyethylene terephthalate as a base polymer, a master batch containing 15% by weight of polytetrafluoroethylene particles, which have average particle diameter of 0.5 as measured by an electron microscope, was prepared.

With the prepared master batch, a polyethylene terephthalate hollow fiber comprising 48 filaments with 150 denier was produced by a spinning and direct drawing process. Content of polytetrafluoroethylene particles in the hollow fiber was controlled to 1% by weight by regulating content of the master batch. The hollow fiber had a hollow rate of about 30%.

88 strands of the fibers were produced in a drum with 4 kg capacity, woven by means of an interlock circular knitting machine with 22 gauge, and dried at a rate of 30 m/min using a hot air dryer after dyeing at 130° C. for 60 minutes to complete a circular knitted fabric.

A result of measuring an abrasion resistance number of the produced fabric is shown in Table 1.

Example 7

Using polyethylene terephthalate as a base polymer, a master batch containing 15% by weight of polytetrafluoroethylene particles, which have average particle diameter of 1.8 μm as measured by an electron microscope, was prepared.

With the prepared master batch, a polyethylene terephthalate hollow fiber comprising 48 filaments with 150 denier was produced by a spinning and direct drawing process. Content of polytetrafluoroethylene particles in the hollow fiber was controlled to 2% by weight by regulating content of the master batch. The hollow fiber had a hollow rate of about 30%.

88 strands of the fibers were produced in a drum with 4 kg capacity, woven by means of an interlock circular knitting machine with 22 gauge, and dried at a rate of 30 m/min using a hot air dryer after dyeing at 130° C. for 60 minutes to produce a circular knitted fabric.

A result of measuring an abrasion resistance number of the produced fabric is shown in Table 1.

Comparative Example 1

A polyethylene terephthalate fiber comprising 36 filaments with 75 denier and a circular knitted fabric comprising the same were prepared by the same procedure as in. Example 1, except that polyethylene terephthalate without polytetrafluoroethylene was used.

A result of measuring an abrasion resistance number of the produced fabric is shown in Table 1.

Comparative Example 2

A polyethylene terephthalate fiber and a circular knitted fabric comprising the same were prepared by the same procedure as in Example 1, except that average particle diameter of polytetrafluoroethylene particles was altered to 0.001 μm.

A result of measuring an abrasion resistance number of the produced fabric is shown in Table 1.

Comparative Example 3

A sea-island type composite fiber and a circular knitted fabric comprising the same were prepared by the same procedure as in Example 5, except that polyethylene terephthalate without polytetrafluoroethylene was used as the island components.

A result of measuring an abrasion resistance number of the produced fabric is shown in Table 1.

Comparative Example 4

A sea-island type composite fiber and a circular knitted fabric comprising the same were prepared by the same procedure as in Example 5, except that average particle diameter of polytetrafluoroethylene particles was altered to 0.001 μm.

A result of measuring an abrasion resistance number of the produced fabric is shown in Table 1.

Comparative Example 5

A polyethylene terephthalate hollow fiber comprising 48 filaments with 150 denier and a circular knitted fabric comprising the same were prepared by the same procedure as in Example 6, except that polyethylene terephthalate without polytetrafluoroethylene was used.

A result of measuring an abrasion resistance number of the produced fabric is shown in Table 1.

Comparative Example 6

There was an attempt to prepare a polyethylene terephthalate hollow fiber by the same procedure as in Example 6, except that average particle diameter of polytetrafluoroethylene particles was altered to 7.0 μm. However, the desired hollow fiber was not produced in a commercially available scale due to severe cutting of yarn during spinning.

With regard to Examples 1 to 7 and Comparative Examples 1 to 6, abrasion resistance numbers of circular knitted fabrics were determined according to ASTM-D3884 experiment for knitted products by means of an evaluation device, for example, a Martin abrasion tester together with 320Cw sandpaper as an abrasive cloth and with applied load of 500 g.

TABLE 1 Example number Abrasion resistance number (times) Example 1 710 Example 2 900 Example 3 2,200 Example 4 3,000 Example 5 32 Example 6 27 Example 7 32 Comparative example 1 350 Comparative example 2 1,000 Comparative example 3 13 Comparative example 4 15 Comparative example 5 12 Comparative example 6 Not detectable

INDUSTRIAL APPLICABILITY

As described in detail above, the thermoplastic fiber with excellent durability of the present invention is preferably used in various applications. More particularly, the inventive thermoplastic fiber can reinforce durability and abrasion resistance of light weight fabrics with small finenesses, which are commercially available for garments. On the other hand, the thermoplastic fiber of the present invention can be broadly applied to footwear, furniture, fabrics for protection wears such as riding coats and bike clothes, in addition to, fabrics for mountain-climbing backpacks. Further, the thermoplastic fiber can be employed in industrial applications such as abrasive materials requiring excellent surface friction resistance properties.

While the present invention has been described with reference to the above preferred embodiments, it will be understood by those skilled in the art that various modifications and variations may be made therein without departing from the scope of the present invention as defined by the appended claims. 

1. A thermoplastic fiber with excellent durability comprising thermoplastic resin, in which fluoropolymer particles having average particle diameter in the range from 0.01 to 5.0 μm are contained in the thermoplastic resin.
 2. The thermoplastic fiber according to claim 1, wherein the fiber has monofilament fineness of not more than 20 denier.
 3. The thermoplastic fiber according to claim 1, wherein content of the fluoropolymer ranges from 0.1 to 9.0% by weight.
 4. The thermoplastic fiber according to claim 1, wherein the fluoropolymer particles have average particle diameter ranging from 0.1 to 1.0 μm.
 5. The thermoplastic fiber according to claim 1, wherein the fluoropolymer comprises at least one selected from a group consisting of polytetrafluoroethylene polymer, copolymer of tetrafluoroethylene and hexafluoropropene, copolymer of tetrafluoroethylene and perfluoroalkylvinylether, and terpolymer thereof.
 6. The thermoplastic fiber according to claim 1, wherein the thermoplastic fiber is a sea-island type composite fiber that contains island components with monofilament fineness ranging from 0.001 to 0.3 denier dispersed in sea components formed of alkali releasing and eluting polymer.
 7. The thermoplastic fiber according to claim 6, wherein the island components contain fluoropolymer particles with average particle diameter ranging from 0.01 to 5.0 μm.
 8. The thermoplastic fiber according to claim 1, wherein the thermoplastic fiber is a thermoplastic hollow fiber having hollow portions in cross-sectional area thereof.
 9. The thermoplastic fiber according to claim 1, wherein the thermoplastic hollow fiber has a hollow rate ranging from 10 to 40%.
 10. A fabric comprising the thermoplastic fiber defined in claim
 1. 